Aerodynamic balance control



March 10, 1953 R. F. PRlBll. ET AL 2,630,983

AERODYNAMIC BALANCE CONTROL Filed Feb. 2l; 1950 5 Sheets-Sheet l Richard F. Pribil Dale D. Myers &

Ralph B. Schreiber INVENTOR.

T IR PATENT ATTORNEY March 10, 1953 R. F. PRIBH. ET AL AERODYNAMIC BALANCE CONTROL 3 Sheets-Sheet 2 Filed Feb. 21, 1950 8 Ralph B. Schreiber .E N ,Mm ...u A T N E A Richard F. Pribil Dale D Myers -1NVENToR- March 10, 1953 R. F. PRISM. ETAL 2,630,988

AERODYNAMIC BALANCE CONTROL Filed Feb. 2l, 195.0

ichard 1%. Pribil Dale D. Myers 8x Ralph B. Schreiber INVENTOR.

"ll-[BY R PATENT ATTORNEY.

Patented Mar. 10, 1 953 v AERODYNAMIC BALANCE CONTROL Richard F. Pribil, Palos Verdes Estates, Dale D. Myers, Inglewood, and Ralph B. Schreiber, Los Angeles, Calif., assignors to North American Aviation, Inc.

Application February 21, 1950, Serial No. 145,346

Claims.

This invention relates generally to controls and control surfaces, and more particularly to improvements in means for operating controls and aerodynamically balancing control surfaces in aircraft and other vehicles.

The control or pilot force necessary to displace control surfaces from their neutral positions increases materially with the angle of their displacement, particularly in large or high speed aircraft. A number of different meanshas been proposed and utilized for assisting the pilot in overcoming the aerodynamic forces to which these displaced'surfaces are subjected and among the most advantageous and successful of these are the internal pressure balance arrangements of the aerodynamic balance type in which sealed pressure chambers are provided, usually between the nose of the movable surface and the rear portion o-f the airfoil or wing upon which the surface is mounted. Partitioning means such as a balance paddle carried by the surface aids in creating a pressure differential between the upper and lower chambers which when utilized to l assist in the displacement of the control surface materially relieves the strain upon the pilot, as

well as upon the actuating mechanism withinv the control system. The present invention relates to improvements in aerodynamic balancingmeans of the internal pressure balance type and derives several advantageous and desirable results which such pressure balances have not heretofore afforded.

One form of the present invention comprises essentially an adjustable valve means disposed within the balance paddle or nose portion partitioning means of the movable surface in conjunction with a toroue means interposed between the surface actuating mechanism and the control surface. The valve means is normally open when the surface is in its neutral position and remains open for the porting or venting of the chambers while the loads necessary to displace the surface are relatively light. Under higher load conditions, however, the pilot effort or the control force necessary to displace the movable surface causes torsional deflection or twisting of the-torque means, which may be a rod, tube or spring, which force is transmitted mechanically to the valve means; the latter is then partially closed such-that the resulting aerodynamic presof roll as compared to those obtained by prior' movable surface controls. The present improvement also obtains very desirable pilot control forces as a function of pilots effort by controlling the aerodynamic forces on the aerodynamic balance of a control surface.

It is, accordingly, a primary object of the present invention to provide improved means for the .earodynamic balancing of control surfaces and -A further object lies in the provision of an im- .proved aerodynamic balance arrangement in sure differential created on the opposite sides of j the balance paddle assists the pilot in displacing the surface in the desired direction. An advanwhich the deflection of the torque element is transmitted to the valve means'for controlling the flow from one side of the balance -paddle to the other to assist in obtaining more desirable pilot control force application as a function of pilot effort by controlling the aerodynamic forces on` the aerodynamic balance of the control surface. A further object of the present invention is the provision of means to reduce the control stick or pilot forces at high rates o-f airplane roll and to increase these forces at much lower rates of roll than those heretofore obtained by other known control surface balancing systems.

Other objects and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates after reading the following description, in conjunction with the accompanying drawings forming a part hereof, in which:

Fig. 1 is a plan view of an airplane wing having an aileron control surface to which a, form of the improved mechanism of the present invention has been applied;

with the improved mechanism shown in greater detail;

Fig. 3 is a sectional elevation taken along the lines 3-3 of Fig. 2 showing the same mechanism;

Fig. 4 is a sectional elevation taken along the lines 4 4 of Fig. 2 showing certain of the torque bar support and attachment details;

Fig. 5 is a sectional elevation of the valve means shown in Figs. 1, 2 and 3;

Fig. 6 is a plan view, corresponding to the plan view of Fig. 2. showing a modiiied form of the improved mechanism; and

Fig. 7 is a sectional elevational view of ythe mechanism of Fig. 6 as taken along the lines 'I-'I thereof.

Referring now to Fig. i the numeral IB indicates fragmentarily an airplanehaving a fuselage II and a cockpit I2 for the pilot and other occupants. The airplane lllisrprovided--with laterally extending wings I3, 4of .which v.but one .is 1

shown, with the trailing edge of which are associated the ap If: and the aileron I5, for the lateral control of the craft. -|The I.3 :is provided with a spanwise extending rear spar I5 to which are attached the brackets I'I forthe support of the aileron hinge members I8 and I9, having a hinge :aXisfA-A :about which the surface iis :pivotally rotated. 'Forward foi the fnorm'al leadingvedge of .the failero'n TI5 it iis. provided with the balance paddle or :vane 'portion 2i) "for 'the known (purpose J.of tparititioning t-he :chamber I3a creating a lpressure diieren'tial :between its upper and :lower surfaces by virtue of the aerodynamic forces tto which the .deflected :aileron yI5 is .subjected. vFlhespar I'B Aforms'tl'ie 'forward Wallro'f a pressure V:chamber or .compartment i3d Lwhich 'is divided into 'upper fand lower chambers 13C and I 3b, respectively, the balance paddle 2.0 which accordinglyfserves asia partitioning member. `rlThe aileron I5 lis operated fby means of the control stick 2.1!, located in the pilot compartment II'2, connected ito the control cable '22 which is .preferably locked to the llevered:sheave member 23 Vor the fo-re 'and 'aft displacement or Vthe vpush-"pull rod .24.. The xait termina-'l .of the push-pull rod 2li is connected .to thevtorque bar 25, :xed'ly supported :and attached to 'the aileron by the n-rltting 26, and guided at the bearing fitting 2.7, being attached -to Jthe rod 2f -by means -of the attachment lever 28. The torque bar Yis preferably of metal or other resilient "mate-rial land is Yshown as a vsol-id -rodrof circular cross-section, :but may be -of 1other cross-section or tubular, forma-y :even be .a )torsion spring, as .long as it `is capable of torsiona resilience. at its .in-board end `by the fitting 26 and its -outboard Aend .is free .in :the torsional sense sto be twisted. by vthe push-pull rod 24 :and its connectionto the torque bar -25 through Vthe attachment lever 28. The Irtree outer -end fof the torque bar .2.5 is provided with an tattachment lever 129 which .is connected `to the *valve 3 for the opening .2te .in .the balance paddle portion 2Q of the aileron l5 sealed from the spar i8 by the curtain 32.

Referring .now to Figs. 2 yto 5, inclusive, for a clearer .understanding .of the details lo'i `the -a-rrangement `shown in Fig. l, it -Wi-llbe noted that the .push-pull yrod 24 extends rearwardly and downwardly through the'slotY-or clearance `opening .2do .in .the .balance .paddle 23. The rear terminal of .the push-.pull rod 24 is pivotaillyconnected bymeans .of the pivot 23 Ato the lever member 28 which i3 securely v:clamped about the squared ,portion 25a .of .the v torcuie .bar 25. The fitting 2S `has .an ear .or Alaterally extending lug portion 28d within which .the adjustment screws 35 are threadediy mounted and this projecting portion and the screws 3.5; operate within the opening in the adjoining bearing .fitting 2l. This fitting 2 is seemed to the main spar 55a of the .The 'torque ba-r 25 is ffixed aileron I5, and its upper portion provides a bearing support for the rounded portion of the torque -bar 25.

In Figs. 2 and 3 the hinge axis of the aileron I5 is also indicated by the lines A-A, this axis being disposed substantially beneath that of the torque bar 25, and as shown in Fig. .3., the axis A--A is intermediate the torque bar axis and the pivotal lconnection of vthe push-pull rod 24 .at the pivot pin 33. It will, accordingly, be seen that relative movement of the lever 28 with res pect to *the iixed. bearing fitting 21 about the axis of the torque bar 25 is limited by the ad- -jus'table screws 3E and 35, as shown in Fig. 3. 'Theftorqueibarrsupport fitting 26 is also clamped tabout va Asquared portion of the torque bar 25, as at 25h in 'Fig'. '2, 'the tting 26 being secured to .the saileronspar ila. The opposite or outboard end of the torque bar 25, which is also squared as at L25a from the fitting 28 outward, is clampingly engaged by the lever 29. The free end of the liever 2-9 is zpivotaily #connected -to 'the fshort link F31| .by .means for the pivot "-bolt 36 :and the Vopposite terminal `of the link 3J, which 'passes through 'the opening .20h in the panel 220 -and the laileron leading edge ilib, 4is /pivotally connected to `the adjustable valve structure 'Sil by .means fof the pivot `bol-t 2d .engaging the .fbifurcated flugs or .eyes 38. Ehe .gap or .open iarea through ithe valve .230 'afdiacent 'the -pivot 'bolt 37 :and "the :lugs 38 :may be :suitably 'sealed fto y:prevent the relatively .sma'll iiow therethrough, :although 'it has been found :in a slumber fof -actual installations that #this area represents such :a negligible portion of the :to'tarl area of fthe balance `paddle -that the slight reduction `in stick prces which `were obtained :at l`the Apressure :diierentials tdeveloped did not Warrant complete ssealng of gap.

The adjustable A`valve 38 isimounted for limited rotation within the 'substantially rectangular opening 4.28o within the balance paddle 2i), zbeing rockable about :the :end pivot 4:n'iountirrgs 29, the axis of which extends asparrwise of the Wing substantially parallel to :that fof lthe torque bar 25. The pivotalimountings -39 Vare formed byithe rein- .forcing Y plates 48 secured :to the uppera-nd lower facesp the balai-ice paddle '.-2-0 which isialso oriced. or .eut away and is provided with z-a :exible seal :4I dor protrusion :of -the push-pull rod 24 through the :balance paddle iwhile 'the latter is deiiected ,downwardly .as fthe aileron :proper Yis deected .upwardly about its hinge axis -A-A. The valve 30 is formed from a :substantially .S- shaped `fr-ame Velement 42, to the outer faces of which .are .attached the channel-shaped valve plates 43,:44, 45-and 48.. .Asm-aybeseenin Fig. 5, rocking .of I.the valve lassembly 30 about the Aaxis of Vits ,pivotal mounting .39 causes closing of the orice 2!c in .the lpanel .29 -by engagement of the valve pla-te A4 with .the .upper surface of `the panel .2.0 at .the .leading uside of the valve and .engagement of .the .undersur-iace of the .panel .by the valve plate .5 .at the `trailing 'iside of vthe valve 30, as :shown in the .construction lines in Fig. 5.

.The .operation fof the modication shown :in

Figs. .1 to 5 inclusive, ,is .as follows.: Referring to Fig. .1., .in the event .it .is desired to move the aileron 1.5 downwardly by :movement of .thefcontrol Ystick `toward Athe ,port 1or .left Yside Yoi 4the aircraft (.toward the right :of the reader of Fig. vl) such .movement .of the control stick .2J movesthe cable V22, `causing .connterclockwise rotationof the levered sheave 23 :and :forward movement of the push-.pull v.rod 24,. VReferring `now .more particularly to Figs. 2 and forward movement of the .rod .24 tends to rotate ythe lever .28 the clockwise direction about the axis of the torque bar 25, while at the same time tending to rotatev the aileron I5 downwardly or in the same clockwise direction. In operation under light loads, movement of the control stick in the cockpit I2 is transmitted through the cable system and the rod 24, acting upon the arm or lever 28 and tending to rotate the torque bar 25. inasmuch as this torque bar is directly carried by the aileron structure at its terminal 25h by means of the bracket 26, the rotative force applied to the bar will tend to deflect surface I5 in the desired direction. Under such relatively light loads applied through the lever arm fitting 28 the torque bar 25 may rotate slightly (due to a relatively small torsional deflection) within the journal provided in the bearing or housing fitting 21, the loads being transmitted through substantially the entire torque bar 25 from the fitting 28 to its xed anchorage to the aileron at the fitting 26. Under higher load conditions, which are met with at greater angular deflections, the initial effect of the pilots eiort will be to place a torque load upon the torque bar which is secured to the aileron 26, and since the aileron tends to resist deflection, due to the air forces directed against it, the torque bar will twist or torsionally deflect. This twisting or winding action is transmitted through the arm 29 and the link 3| to the valve assembly 30 installed in the balance paddle 20, imparting rotation to the valve in the counterclockwise direction about its pivotal axis at 39, and at least partially closing the vent opening 20c through the paddle.

It will be understood that, as the aileron is deflected downwardly, the pressure within the chamberl I3a in the trailing portion of the wingk I3 is increased beneath the paddle 20 and the curtain seal 32 in the lower chamber I3b, and the pressure above the pad-dle will be reduced within the upper chamber I3c. This creates a pressure differential such that the air within the lower chamber I3b endeavors to escape through the vent or port 20c within the paddle. As the lips 44 and 45 of the valve 30 approach and restrict the flow through the opening in the paddle 29, the aerodynamic balancing eect increases, since there is less opportunity for equalization of the pressures within the balance chambers I3b and I Sc because of such restricted ow through the valve. In the event the loads become sufficiently high, the valve 20 will be fully closed as shown in Fig. 5, giving a completely sealed balance. At the point where the valve becomes closed, i. e., the stop 35 making contact (or 34 in the event the aileron is deilected upwardly) additional pilot effort is entirely directed to the aileron I5 through the bearing or housing fitting 21 secured to the front spar I5a of the aileron. As indicated above, the stops 34 and 35 are adjustable and may beset for any desired;` range of movement according to the control charf acteristics of the individual airplane.

Referring vnow to the modification shown in Figs. 6 and '7, which is also applicable to an airplane as shown in Fig. l, the wing is indicatedby the numeral 50 and the aileron by the numeral 5I. `This modification diiers essentially from that previously described in that the hinge axis of the aileron and the axis of the torsionhas a leading edge 5Ib which extends forwardly to form the balance paddle 52. The wing 50 is provided with a trailing edge spar 50d and the intervening space between the spar 50d and the front edge of the paddle 52 is sealed by the flexiblecurtain 52b. A pressure compartment 50a is formed within the aft portion of the wing 50 and the paddle 52 divides this compartment into upper and lower chambers 59e and 56h, respectively. It will be understood that the aileron control surface 5I is supported from the rear spar 50d of the wing as by means of a plurality of the hinge brackets 69 upon which the aileron is mounted by the eye or hinge tting 6I attached' to the aileron as by the screws 62.

A push-pull rod 53, suitably interconnected within the control system to a control stick as in the case of the push-pull rod in Fig. l, is pivotally connected to the arm or lever element 55 at the pivotal connection 54. The upper terminal of the lever 55 is attached to the free end cfa tubular torque element 56 which is anchored tothe aileron structure at its outer terminal as by the anged fitting 51 and the bracket support 58' Aend of the torque tube 56 at the portion wherein it is reinforced by the inserted pin element 59 and the outer end of the arm 64 is provided with a pivotal connection 65a to the lever 65. The latter is pivotally mounted to the valve pivot 1.66 of the valve assembly 61 within the pivot bearings 68 and S9 attached to the balance paddle 52 as by means of the screws 1I). The valve assembly 6l is mounted within a rectangular opening or orice 52a in the balance paddle in Aa similar manner to that of the previous modification and the valve is provided with similar lip portions 61a. v

The operation of the modification shown in Figs. 6 and 7 is as follows: assuming that it is de sired to l-ower the -aileron 5I the control stick is moved such that the push-pull rod 53 is moved forward or to the left in Fig. 7, tending to rotate the lever arm 515 in the clockwise direction. In the event opposition to such `down-ward deflection of the aileron 5-I is relatively small, and the pilot force is commensurate with such a small load, the clockwise movem-ent of the arm 55 will be transmitted directly to the aileron 5I by transmission y. without appreciable twisting, by the torque tube 56, its end flange 57 and the bracket 58. .In the event deflection of the aileron could be continued indefinitely with the application of such a small pilot force, as would be the cas-e, for example, .were the airplane to be at rest upon the ground, the valve actuating arm 64 would rotate as .aunit with the arm 55 an'd the aileron 5I andsince. there would be no relative movement Y between the arm 64 and the paddle v52, the valve 6l would remain in its neutral wide-open posi- A tion as shown .in Fig. 7. However, such continued deflection of the ailerons during night will meet with increased opposition to displacement against the air flo-Wing past the wing, necessitating a greater control force which will cause twisting of the tubular torque ,mem-ber 56.

:spaanse This .have the ehect ci' causing 'the salve `actuating arm 164 .to move in the-:clockwise direction .through a somevrhatgreater angle than the aileron i5! and its balance paddle 52, with the result that this differential movement, transmitted through ithe .pinua and :the lever Vldcauses cloclowise 'pivot-ation of the valve assembly i6?! about its pivot mount-ing 66 and partial :closing of valve opening 52a. The porting or venting of the vvalve is, accordingly, restricted 'as ithe lips of the valve assembly ll -approach 'the margins of .the valve opening .and the resulting increased pressure diierential in 'favor of 'the lower chamber liilb assis-ts the pilot cr control Vforce in rotating the ail-eron by the provi-sion of :an :aerodynamic balance.

-It will, accord`ingly,benoted that this arrangement provides an improved device for Vadvantageous use .on aerodynamic control surfaces, and `obtains desirable pilot 'control forces :as a function of the pilot :effort by controlling 'the aerodynamic balance of the :control surface. As described above, this is accomplished by Ithedeection lof the torque means or the diieren'tia'l angular .movement between the free and iXed ends of the torque tube 5t imparting the ynecessary movement and adjustment of the valve `=5`I which controls the aerodynamic forces -on the aerodynamic balance by porting air "from yone side of the balance paddle tothe other, or by shutting oi thear flow completely. 'It will :also'be noted that a further desirable result of the presently described mechanism is the reduction inthe control stick Iforces fat high rates of lairplane Aroll and their .increase at lower rates of roll, the magnitude of which is lesser and greater, respectively, than that obtained fbyfpriorcontrol suraceoontrols. Vln constructions of the type disclosed herein, .adequate clearance should Vbe provided yto permit unrestricted movement of the balance paddle particularly alt the 'forward corners of the paddle and at its ends as well vas to insure that the curtain or seal is also unrestricted as the aileron is deflected in either direction. A further advantage of 'the disclosed construction is that it also provides a relatively smooth 'transition from a maximum air leakage deflection V4or neutral position of the aileron, to the minimum leakage position at a predetermined angle o-aileron v deflection.

Other forms and modications of the 'present invention which may occur to those skilled in the art after reading the present description are intended to come within the vscope yand spirit of this invention as more particularly set forth in said balance paddle for contro-l of air ow through said balance paddle from one side of said pressure chamber to the other, each side of said pressure chamber open to the adjacent exterior' of said airioil, and actuating mechanism for 'the operation of said control surface including a torsion element fixed at one terminal to said control surface, said torsion element having an opposite torsionally deflectable portion operatively associated with said valve means, said actuating mechanism including a manually Yoperated element connected to said torsionally deiiectable portiono said torsion-element `for '-adjustmentfo said control surface, Whereby 'application -of 'a manual Vcontrol force to said manually operated element 'and deiiection of said vtorsion element initiates actuation of -said valve means for producing a 'balance eect by creating 'a lpressure diierential 'of said airilow on opposite sides of said balance paddle by `the actuation of said val-ve means in accordancewith the magnitude of themanual control force applied to said actuating means required to displace said control surface by the deflection -of said torsion element.

In aircraft, 'an internal-pressure balance including lan airfoil, a pressure chamber formed Within said fairoil, a control `surface operatively mounted upon 'said 'airfoiL Ysaid control vsurface having va vpartitioning element sealingly tted Aat its edges for movement within said pressure chamber, lsaid partitioning element dividing said chamber into differential pressure vportions each separately communicating With the exterior of said 'airio'iL variable orice means carried by said partitioning element for Vvarying t -e ow of air -rom -one said Vpressure portion of said chamber tothe other ysaid pressure portion, manual actuating means including a vpush-pull rod and a Alever for the Aoperation of said control surface, a deflectable torque tube operatively connected between said :actuating means and said control surface at oppositelyfspaced portions of 'said torque tube, mechanism lconnecting said torque'tube with saidvariable orice means for the varying of said variable orifice upon application ofcontrol forces to said actuating means and deection Yof said torque tube to produce a balance effect in accordance with lthe Torce required "by said :actuating means tooperatesaidcontrol surface, and adjustable Amea-ns including stop elements associated with said lever of said actuating means and said control surface engageable at a predetermined position -o said 'variable orifice with respect to said lcontrol.surface tocause said actuating means to directly operate said Acontrol surface through said engaged-stop lements.

1'3.`In aircraft, an internal pressure balance comprising an airfoil, Ia pressure chamber formed Within said vvairioil, Aa control `surface -movably mounted upon said air'foil, 'said Icontrol surface having :a `pressure lbalance paddle sealingly 'tted at'its :edges for Amovement within said pressure chamber, said balance paddle dividing said chamber Sinto diierentialpressure portions each separately communicating with the exterior lof fsaid airfoil, 'valve :means operatively carried by said balance paddle for 'control of air flow from one portion of said `pressure chamber to the other, torsion means 'having fone terminal anchored to said control surface and can opposite d'eilectable 'terminal movable with respect to said control surface, Aactuating means connected to said 'deflectable terminal fof said .torsionfmeans .for moving said control surface, and operating means including a connection from said deectable terminal of said vtorsion 'means to said valve fmeans initiated by movement of said actuating means andzdeilection of said .torsion means for adiusting said'valve means for controlling said pressure differential for assisting said actuating mea-ns in moving 'said control surface.

1'4j-In aircraft, an internal v.pressure -balance comprising an airfoil, a pressure chamber'formed Within said airfoil, a control surface movably mounted upon said airfoil, said control surface having a pressure balance vpaddle Isealingly tted 'at its edges for movement within said pressure chamber, said balance paddle Idividing said chamber into differential pressure portions each sepai rately communicating with the exterior of said airfoil, valve means including an orifice through said balance paddle and a valve element pivotally carried by said balance paddle for control of air fiow through said orifice in said balance paddle from one said pressure portion of said pressure chamber to the other said portion, actuating means for the operation of said control surface, a torque tube capable of torsional deflection operatively interconnecting said actuating means with said control surface, said torque tube having a free terminal attached to said actuating means and an opposite terminal attached to said control surface, and operating means operatively connecting said torque tube with said valve means initiated by the torsional defiection of said torque tube upon application of forces to saidactuating means for the adjustment of said valve means to produce a balance effect by said balance paddle within said pressure chamber in accordance with the force required by said actuating means to move said control surface by torsionally defiecting said torque tube.

5. In aircraft, an internal pressure balance comprising an airfoil, a pressure chamber formed Within said airfoil, a control surface movably mounted upon said airfoil, said control surface having a pressure balance paddle sealingly fitted at its edges for movement within said pressure chamber, said balance paddle dividing said chamber into differential pressure portions each separately communicating with 'the exterior of said airfoil, said balance paddle having an orifice therethrough, valve means pivotally carried vby said balance paddle for control of air fiow through said orifice from one portion of said pressure chamber to the other, and actuating means including a deflectable torque element for moving s aid control surface, said deflectable torque element having a first terminal anchored to said control surface and an oppositely disposed defiectable terminal connected to said valve means and to said actuating means, said torque element connected to said actuating means, said control surface and said valve means in such manner that movement of said actuating means and deflection of said torque element initiates adjustment of said valve means controlling said orifice and the pressure differential across said balance paddle for assisting said actuating means in moving said control surface.

6. In aircraft, an internal pressure balance including an airfoil, a pressure chamber formed within the trailing portion of said airfoil, a control surface operatively mounted upon said airfoil, said control surface having a partitioning element sealing fitted at its edges for relatively air-tight movement Within said pressure chamber, said partitioning element dividing said chamber into differential pressure portions each separately communicating with the exterior of said airfoil, variable orifice means carried by said partitioning element for varying the flow of air from one said pressure portion of said chamber to the other said portion, actuating means for the operation of said control surface, and torque means including a torsionally resilient element operatively connecting said actuating means with said control surface, said torsionally resilient element having a relatively fixed portion attached to said control surface and a relatively movable portion operatively connected to said actuating means and to said variable orifice means, arranged in such manner that application of control force to said actuating means and torsional deflection of said torsionally resilient element causes varying of said variable orifice means carried by said partitioning element to produce a balance effect upon said partitioning element in accordance With the force required by said actuating means to operate said control surface vas refiected by the torsional deflection of said resilient element.

7. In an internal pressure balance for an aircraft including an airfoil, a pressure chamber formed within the trailing portion of said airfoil, a control surface operatively mounted upon said airfoil, actuating means including a pushpull rod for the operation of said control surface, and a partitioning element carried by said control surface sealingly fitted at its edges for movement in a relatively air-tight manner throughout its movement within said pressure chamber, said partitioning element dividing said chamber into differential pressure portions each separately communicating with the exterior of said airfoil, the improvement comprising variable orifice means carried by said partitioning element varying the fiow of air from one said pressure portion of said chamber to the other said portion, and deflectable torque means operatively connected between said push-pull rod of said actuating means and said control surface, said torque means having a fixed portion connected to said control surface, said torque means having a deflectable portion eccentrically connected to said actuating means and an adjacent deflectable portion connected to said variable orifice means, application of control surface operating forces to said actuating means initiating deflection of said torque means and operation of said variable orifice means to produce a balanced effect in accordance With the force required by said actuating means to operate said control surface irrespective of the position of said control surface with respect to said airfoil.

8. In an aircraft, an internal. pressure balance including an airfoil, a pressure chamber formed Within the trailing portion of said airfoil, a control surface operatively mounted upon said airfoil, said control surface having a partitioning element sealingly fitted at its edges for relatively air-tight movements Within said pressure chamber, said partitioning element dividing said chamber into differential pressure portions each separately communicating With the exterior of said airfoil, variable orifice means carried by said partitioning element for varying the iiow of air from one said pressure portion of said chamber to the other said portion, and actuating means for the operation of said control surface, including a torsionally deflectable element operatively connected at a fixed portion of said deflectable elementl to said control surface, said deflectable element connected at a deflectable portion to said variable orifice means whereby movement of said actuating means for operation of said control surface and torsional deflection of said deflectable element causes closing movement of said variable orifice means proportional to deflection of said torsionally deflectable element to produce a pressure balance effect across said partitioning element.

9. In an internal pressure balance installation for an aircraft, the combination with an airfoil, a pressure chamber formed within said airfoil, a control surface movably mounted upon said airfoil, said control surface having a pressure 'balance paddle sealingly tted at its edges for vmovement Within said' pressure chamber, said balance paddle dividing said chamber into difierential' pressure portions each separately communicating with the exterior of'` said airfoil, said balance paddle havingA an orifice therein, a valve element pivotally carried by said balance. paddle for; control of air How through said orice. in said' balance paddle from one said pressure. por,- ltion4 of said pressure chamber to the other. said portion, and an actuating element connected for the operation of said control surface, of torque means capable of torsional deflectionoperativelig interconnecting` said actuating means with said control surface, and operating means connecting a torsionally defiectable portion of said torque means initiated. by theV application of a control` force to said actuating element and the torsional' deflection of said torque means for regulation of said valve elementv to produce a balanced effect as aY function of the. force required by" said actuating element. to, move. said control surface.

10; In aircraft; an internal. pressurev balance including an airfoilg, a pressure chamber formed Within said airfoil;A al control' surface movably mounted' upon a spanwiset axis supported from said airf'oil, said' controlsurf'acev havingI a pressure balance paddlev sealingl'y ttedY at. its. edges for'movement Withinsaid. pressure. chamber, said balance paddle dividing,sai'd'chamber into differ.- ential" pressure portions each separately communicating with theexterior of.' saidarfoil, valve. means, includingan; orifice through. said. balance paddle and al valve. element pivotally carried by said balance paddle for. control of, air flow.

Athrough said o rce in. said. balance paddlefroxn one said pressure-portion of. said pressure cham,- ber to the othery said portion, actuating means for the operation of said control surface includ.- ing a. torsion. tube having an axis disposed in alignment Withthe'axis of said control surface, said torsontube. operatively interconnecting said valve. means with said control surface at longitudinally spaced and. relatively defiectable points along the axis of said. torsion tube, one of said spacedy points` lixed tosaid. control surface.- and manually operated. means for applying a control force. eccentricallvV of said torsion tube axis at the other deflectablev point. thereon. for operating said control surface to.. thereby initiate the ad.- justment of said. valve.r means; to produce apressure balanced effecty in said pressure. portions: in accordance-with the. pilot force required byv said actuating means to movesaidcontrol: surface by torsionallydeecting said torque tube;

' RICHARD F. PRI-BIL.

DALE'D. MYERS. RALPH B. SCHREIB-ERL..

REFIERE-NCES CIlEDy The following references are of" record in: the le. off; this: patent:

UNITED s'rirrnsi PATENTS' Number Namef Eate 2,368,059.v White- Jan: 23;, 1945. 2,370,845-l Davis Mar. 6, ,1945:

FOREIGN' PATENTS Number Country. Dateq 441,603.. Erance May 30;.191-2.

. 431,538.. GreatlBritain Sappi-.19.38;- 

